A plan to pay prisoners from outside Europe a package of up to £2,500 to leave the UK has been criticised.
Only prisoners from outside Europe would be eligible
Home Secretary John Reid outlined the plan as part of a scheme to try and ease the UK's overcrowded prisons.
But the £20m scheme was denounced as a "waste of taxpayers' money" by Mark Leech of the Prison Handbook, a guide to the England and Wales' penal system.
Both Tory and Lib Dems home affairs spokesmen criticised the plan, amid the use of police cells to house prisoners.
'Bribe' and 'incompetence'
Mr Leech said: "This means the taxpayer will have to stump up around £20m to pay for this gimmick - it is completely insane and unfair and it should stop right now."
"I am outraged by this disgusting bribe. Prisoners in England and Wales receive a paltry £47 to last them a fortnight when they are released and yet foreign national prisoners are being bribed with 50 times that amount to leave the country."
Liberal Democrat home affairs spokesman Nick Clegg called the plan a "bribe" and said Mr Reid was guilty of "Keystone Cops incompetence".
"What has the Home Secretary been doing for the last six months if his efforts to solve the foreign prisoner crisis now amount to a vague pledge to sort the problem out by next spring, and an even vaguer plan to bribe them to go back home?"
Shadow home secretary David Davis said of the £2,500 bonus plan: "By definition, these are not people who you can trust to be honest.
"Have we got the border controls to make this work? The answer is no. How will we stop these people ripping off the taxpayer and coming back?"
Prisons minister Gerry Sutcliffe said the deal was "good value for money" if compared to the £37,000-a-year cost of a place in prison.
A Home Office spokesman said the deal would not include giving cash handouts to prisoners.
The money instead would be spent on grants for accommodation, education, or training to help set up a business if they agree to be moved out of the UK.
Mr Reid said the introduction of Operation Safeguard - which involves the use of police cells to house prisoners from overflowing jails - would begin with a "facility" for at 500 places.
The prison population reached a record 79,843 at the weekend, and in theory there were just 125 more spaces left.